Connector for fractured bones

ABSTRACT

A sleeve is to be inserted into a fractured bone bridging the fracture thereof. The leading end portion is then to be located in one bone fragment and the open trailing end portion is to communicate with the exterior of the other bone fragment. An expander screw is threaded into the sleeve and has a head which bears exclusively upon an annular shoulder provided on the sleeve. The front end of the expander screw serves, by its configuration or by cooperation with an expander element, for expanding the leading end of the sleeve so as to retain it in the bone fragment in which it is located. A cap screw is threadedly connected with and closes the trailing end portion of the sleeve, bearing upon the other bone fragment and thereby drawing the two fragments together via the intermediary of the sleeve.

United States Patent Fischer et al.

[451 July 25,1972

[54] CONNECTOR FOR F RACTURED BONES Altheimer Str. 219, Jean-Nicolas[72] Inventors: Artur Fischer,

Tumlingen, Germany; Muller, Strassburg, France [73] Assignee: saidFischer, by said Muller [22] Filed: Oct. 1, 1970 [21] Appl. No.: 77,267

[30] Foreign Application Priority Data Oct. 3, 1969 Germany ..P 19 49922.0 Dec. 29, 1969 Germany ..P 19 65 350.0

[52] U.S. Cl. ..128/92 BB [51] Int. Cl. ...A61f 5/04 [58] Field ofSearch 128/92 BB, 92 R, 92 CA, 92 BC, 128/92 B, 92 D [56] ReferencesCited UNITED STATES PATENTS 2,381,050 8/1945 Hardinge ..128/92 BB2,699,774 1/1955 Livingston ..128/92 BB 2,243,717 5/1941 Moreira..128/92 BB 2,121,193 6/1938 Hanicke ....l28/92 BB 2,490,364 l2/1949Livingston ..128/92 BB Primal Examiner-Richard A. Gaudet AssistantExaminer.l. Yasko Attorney-Michael S. Striker [5 7] ABSTRACT A sleeve isto be inserted into a fractured bone bridging the fracture thereof. Theleading end portion is then to be located in one bone fragment and theopen trailing end portion is to communicate with the exterior of theother bone fragment. An expander screw is threaded into the sleeve andhas a head which bears exclusively upon an annular shoulder provided onthe sleeve. The front end of the expander screw serves, by itsconfiguration or by cooperation with an expander element, for

expanding the leading end of the sleeve so as to retain it in the bonefragment in which it is located. A cap screw is threadedly connectedwith and closes the trailing end portion of the sleeve, bearing upon theother bone fragment and thereby drawing the two fragments together viathe intermediary of the sleeve.

6 Claims, 2 Drawing figures Patented July 25, 1972 3,678,925

//2 V8 for. I

g I f/ortl/ 1 CONNECTOR FOR FRACTURED BONES BACKGROUND OF THE INVENTIONThe present invention relates generally to a connector for fracturedbones, and in particular to a connector for use in case of fractures ofthe neck of the femur, that is the upper thigh bone.

When a bone is fractured, that is when it is cracked and broken in twopieces-a so-called simple fracture as opposed to a compound fracture"where there is more than one break but in which case the generalprinciple to be discussed here is also applicableit must be connectedtogether in its normal position while it mends. In many instances,including where it is necessary to repair a fracture of the femur orupper thigh bone which hereafter will be used for purposes of explainingthe background as well as the present invention, it is customary todrive a nail or pin under a requisite specific angle to the femur intothe neck of the femur. This connects the broken-off neck with theremainder of the femur and locates the two bone fragments in theirrequisite relative position until such natural healing processes-Le. theformation of callus have permanently reunited the two bone fragments.

The problem with this prior-art approach is that while the two bonefragments can be located in proper position relative to one another, itis not possible to draw them together to such an extent as to eliminatethe cap at the fracture line. This, however, is desirable because thesmaller the cap ismeaning the closer the juxtaposed surfaces of the twobone fragments are-the more readily healing will occur and the formationof callus will take place. According to the prior art, however, it isnot only not possible to reduce the gap but in fact the gap is somewhatincreased as a result of driving the nail into the two bone fragments.

SUMMARY OF THE INVENTION It is, accordingly, an object of the presentinvention to provide a connector for bone fragments, particularly butnot exclusively for fractured femurs, which is not possessed of thesedisadvantages.

Still more specifically it is an object of the present invention toprovide such a connector which will so connect the bone fragments as tospeed the healing process which reconnects the fragments into a unitarybone.

A concomitant object of the invention is to provide such a connectorwhich makes it possible to immediately put stress on the fractured bonewithout doing any damage.

In pursuance of the above objects, and others which will become apparenthereafter, one feature of the invention recites, briefly stated, in aconnector for fractured bones which comprises a sleeve adapted forinsertion into a fractured bone bridging the fracture thereof, andhaving a leading end portion adapted to be located in one bone fragmentand an open trailing end portion adapted to communicate with theexterior of the other bone fragment. Expander means is provided forexpanding the leading end portion and includes an expander screwthreaded through the sleeve and having a head portion located within thetrailing end portion engaging and bearing only upon the same when thescrew is rotated in a sense effecting expanding of the leading endportion. A cap screw is threadedly connected with and closes thetrailing end portion of the sleeve.

A connector constructed according to the present invention fulfills therequirements which have been outlined above. It can be readily installedin that a nail is first driven in conventional manner into the two bonefragments to be connected. In the case of a fractured femur the nail isdriven centrally at the requisite angle into the neck of the femur. Nowthe sleeve of the connector according to the present invention is placedaround the nail and driven into the bone, and subsequently the nail iswithdrawn because it is no longer needed. The expander means is nowutilized for expanding the leading end portion of the sleeve whereby thelatter is anchored in the bone. According to the invention the head ofthe expanding screw bears only upon the sleeve itself so that the entireaxial force necessary for effecting the expansion of the leading endportion of the sleeve acts only upon the latter, and not upon the bone.This prevents damage to the bone. Now the cap screw is threaded onto orinto the trailing end of the sleeve and its cap screw head engages andbears upon the exterior of that bone fragment in which the end portionof the sleeve is embedded. Turning of the cap screw in a sense threadingit more deeply onto the sleeve exerts pull upon the sleeve whereby thetwo bone fragments are drawn together and the gap at their fracture lineis reduced or eliminated. Preferably the bone fragments should toucheach other at the fracture line and in this manner the bone fracturewill heal much more rapidly than heretofore possible. Moreover, the bonefragments now are in contact with one another rather than being spacedfrom one another as in the prior art, so that stress can immediately beplaced on the fractured bone once it has been connected with theconnector according to the present invention. 7

When the bone fragments are reunited, that is when the fracture ishealed, the connector is no longer needed. At that time, therefore, thecap screw is unthreaded from the sleeve, and the expanding screw issimilarly unthreaded and removed. The expander member, if a separate onehas been employed which of course is located at the leading end of thesleeve, is dislodged in suitable manner, for instance by exerting abrief blow upon the screw before the latter is unthreaded, so that theexpander member returns to its original position and permits the leadingend of the sleeve to resiliently return to its original configuration,making it possible to subsequently remove the sleeve also.

According to one embodiment of the invention the rear or trailingportion of the sleeve has a stepped outer diameter, meaning that itsouter diameter is less than that of the remainder of the sleeve. Thisportion of reduced outer diameter is provided with external screwthreads which mesh with internal screw threads in the tubular stem ofthe cap screw whose outer diameter corresponds to the outer diameter ofthe remainder of the sleeve. Thus the hole which is formed in the boneas the sleeve is driven into it, will already have sufficient diameterto accommodate the cap screw when the latter is to be threaded onto thetrailing end portion of the sleeve.

It is also possible in accordance with a further embodiment of theinvention to provide the leading end portion of the sleeve at its openleading end with an inwardly directed flange which prevents theundesired emergence from this leading end of the expander member, andconsequently prevents the expander member from becoming dislodged fromthe sleeve.

According to still another embodiment of the invention the leading endportion of the sleeve which is to be expanded may be surrounded with anelastic jacket. The reason for this is that it has been found that theformation of callus during healing takes place not only at the fracturebut also between the segments of the leading end portion of the sleeve,it being understood that this leading end portion will normally beaxially slotted to subdivide it into a plurality of segments or tonguesin order to permit more ready expansion when needed. The formation ofcallus between the segments, however, would prevent proper elasticreturn of the segments to their original position when it is desired todislodge the sleeve after healing. In fact, it might make such returnimpossible and would then force the sleeve to remain in the bone. Theuse of an elastic jacket, however, makes the formation of callus in andaround the segments impossible so that they can return to their originalundeflected position when the expander member is dislodged, and thesleeve can then be properly removed.

It is also possible to construct the front portion of the expander screwas a pin having a conical or otherwise configurated leading end which,when the screw is threaded deeper into the sleeve, serves to expand theexpander member itself rather than drawing the latter into the sleevefor expanding the same. In such a construction it is possible not onlyto obtain good expanding action but also to make all componentsinvolved, including the outer diameter of the sleeve, very small so thatthe connector according to the present invention can be successfullyused even for repairing bone fractures in children without undulyweakening the bones of children-which are not yet very large-with'alarge hole driven into them.

Also, it is possible to configurate thecap screw in such a manner thatits stem does not exteriorly surround the trailing or rear end portionof the sleeve, but instead fits into the interior of the latter. In thiscase of course the stem of the cap screw must be exteriorly threaded tomesh with interior threads of the sleeve, and according to the inventionthe threads onthe stem and the threads on the expander screw, or on thescrew portion of the expander pin, will be identical whereby a simpleand inexpensive manufacture of the various components is furtherfacilitated.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic sectionedillustration showing one embodiment of the invention connecting thefragments of a fractured femur; and

FIG. 2 is a view similar to FIG. 1 but showing another embodiment of theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now firstly theembodiment illustrated in FIG. 1 it will be seen that reference numerals6 and 6' identify the two bone fragments into which a femur has becomeseparated due to a fracture. In the drawing these two bone fragmentshave been properly aligned with reference to one another in the mannerin which they were originally positioned when the bone was not yetfractured In this manner they are connected by means of the illustratedconnector according to one embodiment of the invention. Referencenumeral 1 identifies the connector in toto and it is to be understoodthat preferably the components of the connector are manufactured ofrust-free steel, for instance of steel known under the designation V2Aor that known under the designation V4A. The connector 1 comprises anexpansion sleeve 2, whose front end portion is driven into the bonefragment 6, whereas its rear end portion is located in the bone fragment6 through which the front end portion was originally driven. The rearend of the trailing or rear end portion of the sleeve 2 is open to theexterior of the bone fragment 6', as illustrated.

Located at the front end portion of the sleeve 2 is an expander portion3, and the rear end portion which is stepped, that is which has a lesserouter diameter than the remainder of the sleeve 2, is identified withreference numeral 4. It is also exteriorly threaded and an interiorlythreaded tubular stem of a cap screw can be threaded onto it as shown inFIG. 1.

Located within the expander portion 3, which is for instance created byproviding the leading end portion of the sleeve 2 with axially extendingcircumferentially spaced slots to subdivide it into individual tonguesor sections, is an expander element 7 which can mesh with the expanderscrew 8 threaded into the interior of the sleeve 2. The head 9 of theexpander screw 8 is of such dimensions that it engages the rear end faceat the rear end of the sleeve 2 as shown in the drawing, or else it canactually be located within the sleeve and engage an inner annularshoulder provided for this purpose. In any case, as the screw 8 isthreaded into the sleeve 2 in a sense drawing the expander element 7rearwardly into the sleeve and thereby expanding the expander portion 3due to the entry of the divergent expander element 7, the axial forcesnecessary to effect such expansion are transmitted exclusively into thesleeve 2 by virtue of the fact that the head 9 of the screw 8 bears onlyupon the sleeve 2.

Preferably, although not necessarily, the sleeve 2 is exteriorlyprovided with projections 10 or other similar means for preventing itsrotation with reference to the bone fragments 6, 6.

Once the expander portion 3 has been expanded, the cap screw is threadedonto the trailing end portion 4 of the sleeve 2. In order to be able totransmit the necessary torque required for drawing the bone fragments6,6 together until they abut at the fracture line, the cap screw 5 isprovided with a cap screw head or flange 11 which bears upon theexterior of the bone fragment 6'. To increase the surface with which theflange 11 can bear upon the bone fragment 6 it is possible to provide awasher 12 as illustrated.

To increase the elasticity and ability for radially outward deflectionof the expander portion 3, an annular groove I3 is provided on thesleeve 2 exteriorly encircling the same at the junction with theexpander portion 3. An elastically deflectable jacket 14 is pushed ontoand surrounds the expander portion 3 and is expanded together with thelatter, the purpose being to prevent the growth of callus between thesections of the expander portion 3. The jacket 14 is removed togetherwith the sleeve 2 when the fracture is healed.

In the embodiment of FIG. 2 like elements are identified with likereference numerals. Here, however, the expansion of the expander portion3 is effected by constructing the expander memberv 7a as an actualportion of the screw serving for expanding purposes, or, putting itconversely, to construct the screw in a pin-shaped configuration havinga tapering leading end 17 as illustrated and an exteriorly threaded head15 which meshes with the interior threads in the sleeve 2. In this casethe expander portion 3, having a bore corresponding to the taperingconfiguration of the leading end portion 17, is expanded by threadingthev screw head 15 deeper into the sleeve 2 in a sense advancing the pin7a forwardly, that is towards the left in FIG. 2.

Once anchoring is accomplished, the bone fragments 6 and 6' are drawntogether into abutment by threading the cap screw 5a into the interiorthreads of the sleeve 2 as illustrated. Of course, in this case the stemof the cap screw is exteriorly threaded as will be appreciated.Reference numeral 16 identifies a slot in the head 15 of the pin 7a forfacilitating turning of the latter. As the head of the cap screw 5abears upon the exterior of the bone fragment 6', the sleeve 2 is drawnin the direction towards this head and thereby the bone fragment 6 isdrawn into tight abutment with the bone fragment 6. FIG. 2 also showsthat the washer 12a can be configurated in such a manner--compare thesingle or plural projections l2b--that it will serve not only toincrease the abutment'surface between the head of the cap screw 5a andthe bone fragment 6', but also will serve as a retaining element forpreventing undesired loosening of the cap screw 5a for which purpose itis provided-in addition to the projections l2bwith a tongue 12cvengaging and preventing turning of the head of the cap screw 5a.

In addition to the advantages which already have been out lined asafiorded by the present invention, a further advantage is the fact thatthe connector according to the present inven tion has an identicaldiameter over its entire exterior-this being true in FIG. 1 also whenthe cap screw is connected with the sleeve-and thereby can be producedin a simple and relatively inexpensive manner, and also can be veryreadily and simply inserted into the bone fragments.

While it has been pointed out that the constituent components of theconnector are advantageously made of rustfree or stainless steel, suchas V2A or V4A, it will be appreciated that other materials may also besuitable and are intended to be included in the scope and concept ofthis disclosure. Sleeve 14 may be of synthetic plastic, elasticallydeflectable steel, or the like.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in aconnecting element for bone fragments, it is not intended to be limitedto the details shown, since various modifications and structural changesmay be made without departing in any way from the spirit of the presentinvention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

We claim:

1. A connector for fractured bones, comprising a sleeve adapted forinserting into a fractured bone bridging the fracture thereof, andhaving a leading portion adapted to be located in one bone fragment andan open trailing portion adapted to communicate with the exterior of theother bone fragment and provided with an endface and with internalthreads inwardly of said endface; expander means for expanding saidleading portion, and including an expander screw threaded through saidsleeve and having a head portion located in said trailing portionaxially bearing upon the same when said screw is rotated in a senseeffecting expanding of said leading portion; and a cap screw having astem threaded into said trailing portion of said sleeve and a cap screwhead adapted to exteriorly engage and bear upon said other bonefragment, the threads of said screws being identical.

2. A connector as defined in claim 1, said sleeve having an innerannular shoulder in said trailing portion, and said head engaging andaxially bearing upon said inner annular shoulder when said expanderscrew is rotated for expanding said leading portion.

3. A connector as defined in claim I, wherein said sleeve, expandermeans and cap screw consist of rustfree steel and acid-resistant steel.

4. A connector as defined in claim 1, said sleeve having a radiallyinwardly extending flange at the leading open of said leading endportion.

5. A connector as defined in claim 1, said expander means including anexpander element, and cooperating engaging means on said element andsaid expander screw for drawing the former into said sleeve in a senseexpanding the same in response to rotation of said expander screw.

6. A connector as defined in claim 1, said expander means comprising anexpander member, and an expander pin portion on said screw operative forexpanding said expander member in response to advancement of saidexpander pin portion longitudinally of said sleeve due to rotation ofsaid expander screw.

1. A connector for fractured bones, comprising a sleeve adapted forinserting into a fractured bone bridging the fracture thereof, andhaving a leading portion adapted to be located in one bone fragment andan open trailing portion adapted to communicate with the exterior of theother bone fragment and provided with an endface and with internalthreads inwardly of said endface; expander means for expanding saidleading portion, and including an expander screw threaded through saidsleeve and having a head portion located in said trailing portionaxially bearing upon the same when said screw is rotated in a senseeffecting expanding of said leading portion; and a cap screw having astem threaded into said trailing portion of said sleeve and a cap screwhEad adapted to exteriorly engage and bear upon said other bonefragment, the threads of said screws being identical.
 2. A connector asdefined in claim 1, said sleeve having an inner annular shoulder in saidtrailing portion, and said head engaging and axially bearing upon saidinner annular shoulder when said expander screw is rotated for expandingsaid leading portion.
 3. A connector as defined in claim 1, wherein saidsleeve, expander means and cap screw consist of rustfree steel andacid-resistant steel.
 4. A connector as defined in claim 1, said sleevehaving a radially inwardly extending flange at the leading open of saidleading end portion.
 5. A connector as defined in claim 1, said expandermeans including an expander element, and cooperating engaging means onsaid element and said expander screw for drawing the former into saidsleeve in a sense expanding the same in response to rotation of saidexpander screw.
 6. A connector as defined in claim 1, said expandermeans comprising an expander member, and an expander pin portion on saidscrew operative for expanding said expander member in response toadvancement of said expander pin portion longitudinally of said sleevedue to rotation of said expander screw.